计算个体内投影坐标之间的距离（添加距离列？）

Question

I have a movement dataset with different individuals and projected coordinates. The coordinates were projected into UTM using the following code:

coordinates(data) = ~x+y #turns data into spatial data frame
proj4string(data) <- CRS("+init=epsg:4326")
data <- spTransform(data, CRS("+init=epsg:5321")) #denotes what CRS to use, this changes the data into UTMs from lat/long, which projects the data
data <- as.data.frame(data)

I would like to calculate the distance in meters between coordinates within individuals. I'm okay with a pretty large margin of error as long as it is consistent between points.

Here is a sample of my dataset:

ID      x         y    
Bear1   459486.4  7181992
Bear1   459652.6  7181904
Bear1   459661.5  7181880
Bear2   459604.7  7181898
Bear2   459639.6  7181894
Bear2   459565.1  7181960

Optimally, I'd love a distance column added to this dataset, showing the distance within points.

Answer 1

Please find below a reprex that shows a solution with the sf package.

If I am not wrong, the data you provide are already in EPSG:5321. Assuming this, you only need to enter the following lines of code to get a distance matrix between all the possible pairs of points.

Reprex

• Code

library(sf)

data <- st_as_sf(data, coords = c("x", "y"), crs = 5321)
distances <- st_distance(data)
distances
#> Units: [m]
#>           [,1]      [,2]      [,3]      [,4]      [,5]      [,6]
#> [1,]   0.00000 188.05967 207.85574 151.09894 181.86325  84.95699
#> [2,] 188.05967   0.00000  25.59707  48.27432  16.40122 103.88575
#> [3,] 207.85574  25.59707   0.00000  59.58389  25.99250 125.27155
#> [4,] 151.09894  48.27432  59.58389   0.00000  35.12848  73.56738
#> [5,] 181.86325  16.40122  25.99250  35.12848   0.00000  99.53015
#> [6,]  84.95699 103.88575 125.27155  73.56738  99.53015   0.00000

^{Created on 2021-10-27 by the reprex package (v0.3.0)}

If you want to start from scratch, that is, from geographic coordinates (ie EPSG = 4326), you have to proceed as follows:

library(sf)

data <- st_as_sf(data, coords = c("x", "y"), crs = 4326)
data <- st_transform(data, crs = 5321)
distances <- st_distance(data)
distances

• Your data

data <- data.frame(ID = c("Bear1", "Bear1", "Bear1", "Bear2", "Bear2", "Bear2"),
                   x = c(459486.4, 459652.6, 459661.5, 459604.7, 459639.6, 459565.1),
                   y = c(7181992, 7181904, 7181880, 7181898, 7181894, 7181960))